package com.example.rpc;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 
 * 一个简单的RPC框架
 *
 */
public class RpcFramework {

	/**
	 * 暴露服务
	 * 
	 * @param service:服务实现
	 * 
	 * @param port:服务端口
	 * @throws IOException
	 */
	public static void export(final Object service, int port) {

		try {
			if (service == null) {
				throw new IllegalArgumentException("Service instance is null");
			}
			if (port <= 0 || port > 65534) {
				throw new IllegalArgumentException("Invalid port:" + port);
			}

			System.out.println("Export service " + service.getClass().getName());

			ServerSocket server = new ServerSocket(port);

			for (;;) {
				final Socket socket = server.accept();
				new Thread(() -> {
					try {
						ObjectInputStream input = new ObjectInputStream(socket.getInputStream());

						String methodName = input.readUTF();

						Class<?>[] parameterTypes = (Class<?>[]) input.readObject();
						Object[] arguments = (Object[]) input.readObject();

						ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());

						try {
							Method method = service.getClass().getMethod(methodName, parameterTypes);
							Object result = method.invoke(service, arguments);
							output.writeObject(result);
						} catch (Exception e) {
							output.writeObject(e);
						} finally {
							if (output != null) {
								output.close();
							}
						}
						socket.close();
					} catch (IOException e) {
						e.printStackTrace();
					} catch (ClassNotFoundException e) {
						e.printStackTrace();
					} catch (SecurityException e) {
						e.printStackTrace();
					} catch (IllegalArgumentException e) {
						e.printStackTrace();
					}
				}).start();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@SuppressWarnings("unchecked")
	public static <T> T refer(final Class<T> interfaceClass, final String host, int port) {
		if (interfaceClass == null) {
			throw new IllegalArgumentException("Interface class == null");
		}
		if (!interfaceClass.isInterface()) {
			throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class");
		}
		if (host == null) {
			throw new IllegalArgumentException("Host == null");
		}
		if (port <= 0 || port > 65535) {
			throw new IllegalArgumentException("Invalid port number");
		}
		System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
		return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[] { interfaceClass },
				new InvocationHandler() {
					@Override
					public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

						try (Socket socket = new Socket(host, port);
								ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());) {

							output.writeUTF(method.getName());
							output.writeObject(method.getParameterTypes());
							output.writeObject(args);

							try (ObjectInputStream input = new ObjectInputStream(socket.getInputStream());) {
								Object result = input.readObject();
								if (result instanceof Throwable) {
									throw (Throwable) result;
								}
								return result;
							}
						}
					}

				});
	}
}
